As long as your humidity in your house is close to 50% you shouldn't need any water, if so VERY minimal, like drips. Or you could use something small like a little pepto medicine cup.
For lockdown I have a tube that runs down into the rectangle shape center reservoir, it is attached to a...
Oh and when I did have to add water when I first set it up, I used a tiny dropper and just dropped a couple drips in. I didn't want it going under 25 as in the link below. I didn't put any water in the channels until today for lock down.
I didn't have any problems with mine getting regulated. I have the FI 4200 Pro series.
I followed this method of incubation. https://www.backyardchickens.com/a/how-to-incubate-hatch-eggs-using-the-dry-incubation-method
Now mind you I am on my first hatch, day 19 today, so I can't give any...
Are you going by a built in gauge? Those aren't usually very reliable. At least the one on mine isn't and I have read many others with the same complaint. I would get something like this...